Apparatus and method for positioning an implantable device

ABSTRACT

A catheter assembly for implanting a medical device, comprising a first wire and a second wire, electrically insulated from each other, attached to the medical device at a first attachment point and a second attachment point, respectively. The first wire defines a first region susceptible to electrolytic disintegration, by passing an electric current through it, contiguous to a the first attachment point. Similarly, and the second wire defines a second region susceptible to electrolytic disintegration, by passing an electric current through it, contiguous to the second attachment point. Also, there is a separately controllable electric supply for the first and the second wire, so that the first wire may be disconnected from the medical device, without disconnecting the second wire.

RELATED APPLICATIONS

This application is a continuation-in-part of application serial numberPCT/US12/27259, filed on Mar. 1, 2012 which claims priority fromprovisional application Ser. No. 61/448,459, filed on Mar. 2, 2011 whichare incorporated by reference as if fully set forth herein.

BACKGROUND

The present disclosure is directed to repairing blood vessel defects,such as aneurysms, and other physiological defects or cavities formed inlumens, tissue, and the like, and, more particularly, to an endovascularimplantable device and related endoluminal delivery procedure anddeployment techniques.

Cranial aneurysms occur when a weakened cerebral blood vessel (rootvessel) locally expands to form a bulge or balloon-like enlargement inthe vessel wall. These aneurysms can occur along a vessel wall or atlocations of vessel branches, such as a T-intersection orV-intersection.

Currently, options for the treatment of brain aneurysms are limited. Inone technique, the cranium is opened and a clip is placed at theaneurysm neck to cut off blood flow from the root vessel, therebyreducing swelling and stopping expansion. In another technique, theinterior of the aneurysm is accessed by way of a cranial artery, whichin turn is reached with a device inserted into the femoral artery. Inthis technique, coiling material is inserted into the aneurysm, therebycausing clotting which closes off the aneurysm. Both techniques havedrawbacks. Opening the cranium always entails some risk. Some locationsin the cranium are difficult or impossible to access from the outside.On the other hand, causing clotting in the aneurysm can increase themass and size of the aneurysm, causing it to press against delicate andcritical tissue, and causing further damage.

Devices and techniques have been developed to facilitate treatment ofaneurysms. The application herein is a joint inventor on the followingU.S. Patent Publication Nos. 2006/0264905 (“Improved Catheters”),2006/0264907 (“Catheters Having Stiffening Mechanisms”), 2007/0088387(“Implantable Aneurysm Closure Systems and Methods”), and 2007/0191884(“Methods and Systems for Endovascularly Clipping and Repairing Lumenand Tissue Defects”). All of these published applications areincorporated by reference herein in their entirety, to the extentlegally possible.

For example, referring to FIGS. 1A and 1B, which are reproduced fromU.S. Patent Publication No. 2007/0191884, shown therein is a device 130having a patch or closure structure 131 mounted to or associated withtwo anchoring structures 132, 133. The closure structure 131 issupported by a framework structure 134 that is provided at least in aperimeter portion and is attached to the closure structure 131 by meansof bonding, suturing, or the like. The framework structure 134 ismounted to or associated with the wing-like anchoring structures 132,133. These anchoring structures 132, 133 in a deployed condition aredesigned so that at least a portion thereof contacts an inner wall of ananeurysm or an internal wall of an associated blood vessel followingdeployment.

As can be seen in FIG. 1A, the anchoring structures 132, 133 aregenerally formed to curve outwardly from an attachment joint 135 to theframework structure 134 and then back inwardly toward one another at theend remote from the attachment point 135. The anchoring loops 132, 133are generally of the same configuration and same dimension and arelocated opposite one another as shown in FIG. 1A.

FIG. 1B illustrates a similar device having a closure structure 136 withanchoring structures 137, 138 that attach to or project from a frameworkstructure 139 along opposed, lateral edges of the framework structure.The anchoring structures 137, 138 as illustrated in FIG. 1B are gentlycurved and, at their terminal sections, extend beyond correspondingterminal sections of the framework structure and the closure structure.The closure and framework structures in this embodiment are generallyprovided having a surface area that exceeds the surface area of theaneurysm neck, and the anchoring structures generally reside inside theaneurysm following placement of the device. In this configuration, theanchoring structures exert lateral and downward force on the closurestructure so that it generally conforms to the profile of the vesselwall at the site of the aneurysm, thereby sealing the neck of theaneurysm from flow in the vessel and providing reconstruction of thevessel wall at the site of the aneurysm. Unfortunately, frameworkstructure 139 and structures 137 and 138 are mismatched in length andare too stiff to apply the mutually opposing forces on interposedtissue, necessary to form an effective clip. In addition this structureis too stiff and expanded to be able to collapse into a configurationthat can be fit into the space available in a placement device, smallenough to be introduced into the smaller cranial blood vessels.Moreover, its boxy shape makes it difficult to maneuver as is necessaryto effect placement into an aneurysm.

FIGS. 1C-1F schematically illustrate the devices of FIGS. 1A and 1Bdeployed at the site of an aneurysm. A bulge in the blood vessel B formsan aneurysm A. As shown in FIGS. 1C and 1D, when the device 130 isdeployed across the neck of and within the aneurysm A, the closurestructure 131 is positioned to cover the opening of the aneurysm and theanchoring structures 132 and 133 are retained inside and contact aninner aneurysm wall along at least a portion of their surface area. Inthis fashion, the closure structure 131 and the framework portion 134are supported across the aneurysm opening and are biased against theneck of the aneurysm from outside the aneurysm.

In the embodiment illustrated in FIGS. 1C and 1D, the closure structure131 and the framework portion 134 are deployed outside the internalspace of the aneurysm. In an alternative embodiment illustrated in FIG.1E, the closure structure 131 and the framework portion 134 aresupported across the aneurysm opening and biased against the neck of theaneurysm from inside the aneurysm.

FIG. 1F illustrates an alternative deployment system and methodology,wherein a device having at least two anchoring structures is deployedsuch that the closure structure 131 is positioned to cover the openingof the aneurysm, and the anchoring structures 132, 133 are positionedoutside the aneurysm and contact an inner blood vessel wall B inproximity to the aneurysm. In this embodiment, the anchoring structures132, 133 may be generally sized and configured to match the innerdiameter of the vessel in proximity to the neck of the aneurysm so thatfollowing deployment the anchoring structures contact the vessel wall ina substantially continuous manner without straining or enlarging thevessel wall in the area of the aneurysm. In all of these embodiments,following placement of the device, the closure structure substantiallycovers the aneurysm neck to effectively repair the vessel defect. Theanchoring structures do not substantially interfere with flow of bloodin the vessel.

As can be seen in the foregoing, the structures may be difficult toplace, particularly in the circuitous blood vessel network of the brain.For the typical aneurysm, extending in a perpendicular manner from itsroot blood vessel, it may be a challenge to insert the structure intothe aneurysm. Moreover, for the device to seal or close the aneurysm,the anchoring structures must mutually press against the aneurysm sides.If one side wall of an aneurysm is not well suited for supporting ananchoring structure, the anchor for the opposite side will not be wellsupported to provide sufficient pressure on this opposite side wall.This problem drives the design of anchor structures 132 and 133 to belarger, to facilitate receiving sufficient support from the aneurysminterior surface. This, in turn, has the potential to create a masseffect problem, in which the mass of the structures 132 and 133, plusany clotting that occurs around them, causes the aneurysm to become moremassive, potentially pressing against delicate nervous system tissue asa result.

Moreover, the situation is even more difficult for aneurysms formed atthe intersection of vessels, such as a T-intersection or V-intersection.FIG. 1G illustrates a saccular bifurcation aneurysm 150 appearing at theintersection of two vessels 152, 154, branching from a stem vessel 156.Cerebral bifurcation aneurysms are commonly found at the middle cerebralartery, internal carotid artery, anterior communicating artery, basilarartery, posterior communicating artery, and other locations.

Typically, to place device 130 into a blood vessel of the brain requiresa number of steps. First, an incision is made into the femoral arteryand a sheath is introduced, extending approximately to the aorta. Afirst guide catheter is inserted through the sheath and extended up intothe carotid artery. A second guide catheter is coaxially introducedthrough the first guide catheter and extended up into the targetaneurysm. Both guide catheters are introduced using a guide wire havinga steerable tip of either stainless steel or nitinol. Then,microcatheter introducer is inserted through the guide catheter, to theaneurysm, and device 130 is placed at the aneurysm site. Heretofore,however, once reaching the aneurysm there has been no effective methodfor positioning a device that requires precise positioning. A devicethat would require a definite orientation, at least partially inside theaneurysm, presents particular challenges in positioning duringimplantation

Another difficulty in delivering a complex implant into an aneurysm isthe lack of space to pack such an implant in a lumen at the end of amicrocatheter. Any such device must fold into a cylinder having aninternal diameter on the order of 1 mm and a length of about 10 mm. Upondelivery it must expand to anchor itself in place and to seal an areathat could be as large as 10 mm². The seal over the neck of the aneurysmalthough thinner than 1 mm, must be strong enough to affirmativelyocclude the aneurysm, with a very high degree of certainty.

SUMMARY

The following embodiments and aspects thereof are described andillustrated in conjunction with systems, tools and methods which aremeant to be exemplary and illustrative, not limiting in scope. Invarious embodiments, one or more of the above-described problems havebeen reduced or eliminated, while other embodiments are directed toother improvements.

In a first separate aspect, the present invention may take the form of amethod of implanting a medical device that utilizes an implantationcatheter including a first wire and a second wire, electricallyinsulated from each other, attached to the medical device at a firstattachment point and a second attachment point, respectively. The firstwire defines a first region susceptible to electrolytic disintegration,contiguous to a the first attachment point, and the second wire definesa second region, also susceptible to electrolytic disintegration,contiguous to the second attachment point. The medical device ispositioned at a first desired positioning and electricity is passedthrough the first wire, sufficient to heat and disintegrate the firstregion susceptible to electrolytic disintegration, thereby freeing themedical device from the first wire. Then, the medical device ismanipulated with the second wire to achieve a second desiredpositioning. Finally, electricity is passed through the second wire,sufficient to heat and disintegrate the second region susceptible toelectrolytic disintegration, thereby freeing the medical device from thesecond wire.

In a second separate aspect, the present invention may take the form ofa catheter assembly for implanting a medical device, comprising a firstwire and a second wire, electrically insulated from each other, attachedto the medical device at a first attachment point and a secondattachment point, respectively. The first wire defines a first regionsusceptible to electrolytic disintegration, by passing an electriccurrent through it, contiguous to a the first attachment point.Similarly, and the second wire defines a second region susceptible toelectrolytic disintegration, by passing an electric current through it,contiguous to the second attachment point. Also, there is a separatelycontrollable electric supply for the first and the second wire, so thatthe first wire may be disconnected from the medical device, withoutdisconnecting the second wire.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following detailed descriptions.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Exemplary embodiments are illustrated in referenced drawings. It isintended that the embodiments and figures disclosed herein are to beconsidered illustrative rather than restrictive.

FIG. 1A illustrates an enlarged schematic front isometric view of aknown implantable device in a deployed condition;

FIG. 1B illustrates an enlarged schematic front isometric view ofanother known implantable device in a deployed condition;

FIGS. 1C, 1D, 1E, and 1F schematically illustrate the devices of FIGS.1A and 1B deployed at the site of an aneurysm;

FIG. 1G illustrates a saccular bifurcation aneurysm;

FIG. 2A is a sectional side view of an aneurysm closure device,according to the present invention, installed in the neck of an aneurysmthat has developed at the side of a blood vessel.

FIG. 2B is a sectional side view of the aneurysm closure device of FIG.2A, according to the present invention, installed in the neck of ananeurysm that has developed at a Y-intersection of blood vessels.

FIG. 3 is an isometric view of the aneurysm closure device of FIG. 2A.

FIG. 4 is an isometric view of an implantation catheter, according tothe present invention, with the closure device of FIG. 2A retracted.

FIG. 5 is an isometric view of the catheter of FIG. 4, with the closuredevice of FIG. 2A exposed.

FIG. 6 is an isometric exploded view of the user control portion of thecatheter of FIG. 4.

FIG. 7 is a sectional side view of the distal end of the catheter ofFIG. 4, with the closure device of FIG. 2A retracted.

FIG. 8 is an isometric view of the distal portion of the positioningassembly of FIG. 4, with the closure device of FIG. 2A extended.

FIG. 9 is a cross-sectional view of the distal portion of FIG. 8, takenat view line 9-9.

FIG. 10 is a cross-sectional view of the distal portion of FIG. 8, takenat view line 10-10.

FIG. 11 is a cross-sectional view of the distal portion of FIG. 8, takenat view line 11-11.

FIG. 12A is a side view of the user control of FIG. 6, set in a neutralposition.

FIG. 12B is a side view of the user control of the distal end of FIG. 7,corresponding to the user control setting of FIG. 12A.

FIG. 13A is a side view of the user control of FIG. 6, set in a skewedposition.

FIG. 13B is a side view of the user control of the distal end of FIG. 7,corresponding to the user control setting of FIG. 13A.

FIG. 14A is a side view of the user control of FIG. 6, set in a positionskewed opposite to that of FIG. 13A.

FIG. 14B is a side view of the user control of the distal end of FIG. 7,corresponding to the user control setting of FIG. 12A.

FIG. 15A is an isometric view of a work piece shown connected to thedistal end of FIG. 7 for ease of presentation and representing a stagein the manufacturing of the closure device of FIG. 3.

FIG. 15B is a detail view of a portion of FIG. 15A, as indicated bycircle 15B, in FIG. 15A.

FIG. 15C is an isometric view of a work piece shown connected to thedistal end of FIG. 7 for ease of presentation and representing a furtherstage in the manufacturing of the closure device of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures or components or both associated withendovascular coils, including but not limited to deployment mechanisms,have not been shown or described in order to avoid unnecessarilyobscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification andclaims that follow, the word “comprise” and variations thereof, such as“comprises” and “comprising” are to be construed in an open inclusivesense, that is, as “including, but not limited to.” The foregoingapplies equally to the words “including” and “having.”

Reference throughout this description to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearance of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thespecification are not necessarily all referring to the same embodiment.

Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments.

The present disclosure is directed to closing a bulge or aneurysm formedin blood vessel, such as an artery or vein (referred to more generallyherein as “vessel”), in a manner that does not suffer from some of thedrawbacks of prior art methods. For example, in the prior art methodinvolving the insertion of a wire coil into the aneurysm, the resultantblood clot can create problems through its mass and the possibility ofpressing against nearby nerves. In addition, the wire coil can have theeffect of keeping the neck open, possibly causing another aneurysm toform.

The embodiments of the present disclosure combine the closure structureand the anchoring structure into a single unit to improve compactness,allow delivery into the tortuous intracranial circulation system via amicrocatheter, and to improve the aneurysm neck closure. In addition,the embodiments of the present disclosure provide enhanced rotationcontrol and placement of the device within the aneurysm via twoattachment points for a microcatheter. Moreover, markers can be used atthe junctions of the device structure to aid in tracking the movement ofthe closure device during insertion and placement.

Referring to FIG. 2A, a preferred embodiment of an aneurysm closuredevice 10 is shown in its implanted environment of an aneurysm 12attached to a root vessel 14. FIG. 2B shows the device 10, implantedenvironment, on an aneurysm that has developed at a Y-intersection ofblood vessels. FIG. 3 shows a more detailed perspective view of closuredevice 10. In FIG. 2A, aneurysm closure device 10 is held in place byfour anchors: A first aneurysm anchor 16A and a first root vessel anchor18A mutually anchor closure device 10 to a distal side of the aneurysm12, while a second aneurysm anchor 16B and a second root vessel anchor18B, mutually anchor closure device 10 on a proximal side of theaneurysm 12. Referring to FIG. 3, it is seen that in the installed stateof FIG. 2A, a seal 20 is placed over the neck of aneurysm 12, therebypreventing further blood flow into aneurysm 12 and causing it to atrophyover time.

First anchors 16A and 18A act as a first clip, mutually applying gentlepressure toward each other, thereby clipping about the interposedtissue. In similar manner, second anchors 16B and 18B act as a secondclip. Working together, anchors 16A, 18A, 16B and 18B hold the seal 20in place, thereby blocking the flow of blood into aneurysm 12.

Closure device 10 includes a wire frame 22, which is made of nitinol, orsome other shape-memory material. Prior to use, closure device 10 ismaintained at a temperature below human body temperature, therebycausing wire frame to assume the shape shown in FIG. 3, when firstpushed out of terminal lumen 56. In one preferred embodiment, afterwarming to 37C, however, anchors 16A and 18A, are urged together, as areanchors 16B and 18B, thereby more securely clipping to the interposedtissue. In another preferred embodiment, however, the natural springforce of the nitinol causes device 10 to expand when it is pushed out offossa 56, and it retains this shape during positioning and use. A set ofeyeholes 24 are defined by frame 22 and expanded polytetrafluoroethylene (ePTFE) thread or fiber 26 is threaded into theseeyeholes 24 to form a lattice. The eyeholes 24 are filled with goldsolder (FIG. 15B), thereby anchoring thread 26 and closing eyeholes 24.Accordingly, although materials may be useable as thread 26 whatevermaterial is used must be capable of withstanding the temperature ofmolten gold solder, which is typically 716° C. The ePTFE lattice work 26is then coated with silicone 28, which in one preferred embodiment iscured in situ to form the seal 20. In another preferred embodiment,sheets of silicone are cut to the correct dimensions and adheredtogether about the ePTFE lattice 26. In the embodiment shown, silicone28 is placed on the aneurysm anchors 16A and 16B, but in an alternativeembodiment, the ePTFE portion on anchors 16A and 16B are there tocomplete the threading arrangement, but are not coated with silicone. Inanother alternative preferred embodiment more, and smaller, eyeholes 24are defined. In a preferred embodiment, two spots of radiopaque material30 are placed at the tip of each aneurysm anchor 16A and 16B and onespot of radiopaque material 30 is placed at the tip of each root vesselanchor 18A and 18B. Accordingly, a surgeon placing closure device 10 candetermine the position of closure device 10, through a sequence of X-rayimages, relative to the contours of the aneurysm 12, which is shown bythe use of a radiopaque dye, placed into the bloodstream.

In an alternative preferred embodiment at least some of the anchors,serving the function of anchors 16A-18B, are made of a thin sheet ofnitinol, or a thin sheet of nitinol covered with a biocompatiblesilicone, or polymeric material, for forming a good grip on the tissueit contacts. In yet another embodiment, at least some of the anchors aremade entirely of polymeric material. In an additional preferredembodiment, ePTFE thread 26 lattice, is replaced with metal filigree,made of a metal such as gold, having a high melting point. In addition,there is a broad range of engineered materials that can be created forthis type of purpose. In yet another preferred embodiment, anchors,serving the function of anchors 16A-18B, are made of wire loops or arcs,some of which support an ePTFE reinforced silicone barrier, therebyproviding a closure mechanism for an aneurysm.

Referring to FIGS. 4-14B, prior to installation, closure device 10 formsa part of a micro-catheter closure device installation assembly 40,which although specifically adapted to install closure device 10 at ananeurysm also embodies mechanisms that could be used for other tasks,particularly in accessing tissue through a blood vessel. Assembly 40comprises a micro-catheter subassembly 42, and a user-controlsubassembly 44. A first wire-head handle 46A and a second wire-headhandle 46B, are attached to a first wire 48A and a second wire 48B,respectively.

Referring to FIGS. 7-14B, in micro-catheter subassembly 42, wires 48Aand 48B pass through a flexible tube 50, which has an exterior diameterof about 1.5 mm, and which has a hydrophilic exterior surface, to aid inprogressing toward a blood vessel destination. Tube 50 is divided into aproximal single lumen extent 52, near-distal dual lumen extent 54, and adistal fossa or wide-lumen extent 56. This construction permits for thecontrol of the shape and orientation of distal portion of tube 50, andfor the positioning of closure device 10, after it has been pushed outof fossa 56. As shown in FIG. 13A and 13B, if the first wire-head handle46A is retracted relative to second wire-head handle 46B, then distalfossa 56 bends towards handle 46A. Likewise, as shown in FIGS. 14A and14B, if the second wire-head handle 46B is retracted relative to firstwire-head handle 46A, then distal fossa 56 bends towards handle 46B. Theorientation of fossa 56, and the direction it turns to when handle 46Aor 46B is retracted, can be changed by rotating the wire-head handles46A and 46B, together. After closure device 10 is pushed out of fossa56, it responds in like manner, bending toward wire-head handle 46A,when handle 46A is retracted, and toward handle 46B, when handle 46B isretracted. It can be rotated, and the direction that it bends when wire46A or 46B is pulled can be determined, by rotating the handles 46A and46B, together. This freedom in positioning is important during theimplantation process, when as shown in FIGS. 2A and 2B anchors 16A and16B must be maneuvered through the neck of the aneurysm 12, andpositioned so that they extend along the same dimension as root vessel14. The radiopaque markings 30 (FIG. 3) are invaluable during thisprocess.

Referring now to FIG. 6, subassembly 42 is threaded through an end cap60, and passes into a transparent chamber 62, where wires 48A and 48B,emerge from tube 50, pass through a slider 64 and are separatelyanchored in handles 46A and 46B, respectively. The travel extent ofslider 64 is limited by a stop pin 66 and a slot 68.

In one preferred embodiment, wires 48A and 48B are electrically isolatedfrom each other, either by a thin layer of insulating material or simplyby the layout of device 10 and the conductive characteristics of wires48A and 48B. Each include a region 70 (FIGS. 7 and 8) that issusceptible to electrolytic disintegration. To detach closure device 10,after partial placement and initial orientation, which may be checked byreference to radio opaque markings 30, an electric current is passedthrough wire 48A, causing region 70 of wire 48A to electrolyticallydisintegrate. After this, wire 48B may be used to further orientaneurysm device 10.

Although after the freeing of seal 20 from wire 48A, control may be lesscertain, it may in some instances be possible to have a greater freedomof positioning device 10 when a single wire 48B is attached, only. Thismay be particularly true when a portion of device 10 has contacted bodytissue, for example entering aneurysm 12, and it is desired to orientdevice 10 properly for the setting of anchors 16A and 16B and 18A and18B so that the extend along the length of blood vessel 14. Againverifying orientation by way of markings 30, when device 10 is properlyoriented electricity is passed through wire 48B, causing its region 70to disintegrate, and freeing closure device 10 from wires 48A and 48B,entirely so that it can be left in place in its target location, sealinganeurysm 12. In a preferred embodiment, handles 46A and 46B eachincludes an electrical contact connected to wire 48A and 48B,respectively, for attaching to a source of electricity for performingthe above-described step.

Subassembly 42 is introduced into the femoral artery and guided throughthe carotid artery into the brain's arterial system, and further guidedto the aneurysm 12. At this point closure device 10 is pushed out offossa 56, anchors 16A and 16B are guided into aneurysm 12, and anchors18A and 18B are positioned in root artery 14. Then a pulse ofelectricity severs closure device 10 from wires 48A and 48B and closuredevice 10 is installed in place.

Wires 48A and 48B are made of stainless steel alloy 304, which may alsobe referred to as alloy 18-8. This material is coated with polytetrafluoroethylene, except for at detachment points 70 and the pointswhere they are connected to a source of electricity. The nitinol alloythat frame 22 (FIG. 3) is made of is 54.5% to 57% nickel, with theremainder titanium, which forms a super-elastic alloy. The introducertube 50 is made of high density polyethylene, coated at the distal tipwith a hydrophilic coating. Finally, the silicone 28 of the closuredevice 10 is silicone MED 4820 or MED-6640, which is a high tearstrength liquid silicone elastomer, having a Shore A durometer readingof 20-40. A MED6-161 Silicone Primer is used to attach silicone 28 toNitinol frame 22.

While a number of exemplary aspects and embodiments have been discussedabove, those possessed of skill in the art will recognize certainmodifications, permutations, additions and sub-combinations, thereof. Itis therefore intended that the following appended claims and claimshereafter introduced are interpreted to include all such modifications,permutations, additions and sub-combinations as are within their truespirit and scope.

1. A method of implanting a medical device, including: a. providing animplantation catheter including a first wire and a second wire,electrically insulated from each other, attached to said medical deviceat a first attachment point and a second attachment point, respectively,said first wire defining a first region susceptible to electrolyticdisintegration, contiguous to a said first attachment point, and saidsecond wire defining a second region susceptible to electrolyticdisintegration, contiguous to said second attachment point; b.positioning said medical device at a first desired positioning; c.passing electricity through said first wire, sufficient to heat anddisintegrate said first region susceptible to electrolyticdisintegration, thereby freeing said medical device from said firstwire; and d. manipulating said medical device with said second wire toachieve a second desired positioning; and e. passing electricity throughsaid second wire, sufficient to heat and disintegrate said second regionsusceptible to electrolytic disintegration, thereby freeing said medicaldevice from said second wire.
 2. The method of claim 1, wherein saidmedical device is a aneurysm seal.
 3. The method of claim 1, whereinsaid medical catheter further includes: a. double lumen section,including a first lumen through which said first wire extends and asecond lumen through which said second wire extends; and b. a controlunit, having a first wire control handle affixed to said first wire anda second wire control handle affixed to said second wire, each controlhandle being capable of pushing its affixed wire distally through saidcorresponding lumen or retracting its wire proximally through saidlumen, and where said first and second wire control handles can berotated together to any rotational position.
 4. A catheter assembly forimplanting a medical device, comprising: a. a first wire and a secondwire, electrically insulated from each other, attached to said medicaldevice at a first attachment point and a second attachment point,respectively, said first wire defining a first region susceptible toelectrolytic disintegration, by passing an electric current through it,contiguous to a said first attachment point, and said second wiredefining a second region susceptible to electrolytic disintegration, bypassing an electric current through it, contiguous to said secondattachment point; and b. a separately controllable electric supply forsaid wire and said second wire, so that said first wire may bedisconnected from said medical device, without disconnecting said secondwire.
 5. The catheter assembly of claim 4, wherein said medical catheterfurther includes: a. double lumen section, including a first lumenthrough which said first wire extends and a second lumen through whichsaid second wire extends; and b. a control unit, having a first wirecontrol handle affixed to said first wire and a second wire controlhandle affixed to said second wire, each control handle being capable ofpushing its affixed wire distally through said corresponding lumen orretracting its wire proximally through said lumen, and where said firstand second wire control handles can be rotated together to anyrotational position.